Work continues on the identification and characterization of circulating immune complexes and aggregates in Systemic Lupus Erythematosus and other Connective Tissue Diseases. Particular attention is being paid to cryoprecipitates and complexes which can be precipitated by the first subcomponent of complement (Clq). These complexes are being analyzed for their antibody and antigen content, using DNAse and various proteolytic enzymes (such as pronase and trypsin). Inhibitors of lymphocyte activity are being analyzed and the role of specific globulins such as antilymphocyte antibodies are being evaluated. It has been found that there are two populations of lymphocytes coated with immunoglobulin; one has an easily dissociable coating of immunoglobulin and has been termed an L cell (Ig-labile). The roles of these cells and their interactions are being studied. The affinity and specificity of antiDNA antibodies in SLE and drug induced lupus are being studied. Characteristics of the lymphocyte membrane are being evaluated to see if there is a difference between cells in SLE and normal individuals. The specificity of antilymphocyte membrane are being evaluated to see if there is a difference between cells in SLE and normal individuals. The specificity of antilymphocyte antibodies in SLE and other disorders is simultaneously being characterized.